diff -r 000000000000 -r 6474c204b198 xpcom/base/nsWindowsHelpers.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/base/nsWindowsHelpers.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,187 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsWindowsHelpers_h
+#define nsWindowsHelpers_h
+
+#include <windows.h>
+#include "nsAutoRef.h"
+#include "nscore.h"
+
+// ----------------------------------------------------------------------------
+// Critical Section helper class
+// ----------------------------------------------------------------------------
+
+class AutoCriticalSection
+{
+public:
+  AutoCriticalSection(LPCRITICAL_SECTION section)
+    : mSection(section)
+  {
+    ::EnterCriticalSection(mSection);
+  }
+  ~AutoCriticalSection()
+  {
+    ::LeaveCriticalSection(mSection);
+  }
+private:
+  LPCRITICAL_SECTION mSection;
+};
+
+template<>
+class nsAutoRefTraits<HKEY>
+{
+public:
+  typedef HKEY RawRef;
+  static HKEY Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aFD)
+  {
+    if (aFD != Void()) {
+      RegCloseKey(aFD);
+    }
+  }
+};
+
+template<>
+class nsAutoRefTraits<SC_HANDLE>
+{
+public:
+  typedef SC_HANDLE RawRef;
+  static SC_HANDLE Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aFD)
+  {
+    if (aFD != Void()) {
+      CloseServiceHandle(aFD);
+    }
+  }
+};
+
+template<>
+class nsSimpleRef<HANDLE>
+{
+protected:
+  typedef HANDLE RawRef;
+
+  nsSimpleRef() : mRawRef(nullptr)
+  {
+  }
+
+  nsSimpleRef(RawRef aRawRef) : mRawRef(aRawRef)
+  {
+  }
+
+  bool HaveResource() const
+  {
+    return mRawRef != nullptr && mRawRef != INVALID_HANDLE_VALUE;
+  }
+
+public:
+  RawRef get() const
+  {
+    return mRawRef;
+  }
+
+  static void Release(RawRef aRawRef)
+  {
+    if (aRawRef != nullptr && aRawRef != INVALID_HANDLE_VALUE) {
+      CloseHandle(aRawRef);
+    }
+  }
+  RawRef mRawRef;
+};
+
+
+template<>
+class nsAutoRefTraits<HMODULE>
+{
+public:
+  typedef HMODULE RawRef;
+  static RawRef Void()
+  {
+    return nullptr;
+  }
+
+  static void Release(RawRef aFD)
+  {
+    if (aFD != Void()) {
+      FreeLibrary(aFD);
+    }
+  }
+};
+
+typedef nsAutoRef<HKEY> nsAutoRegKey;
+typedef nsAutoRef<SC_HANDLE> nsAutoServiceHandle;
+typedef nsAutoRef<HANDLE> nsAutoHandle;
+typedef nsAutoRef<HMODULE> nsModuleHandle;
+
+namespace
+{
+  bool
+  IsRunningInWindowsMetro()
+  {
+    static bool alreadyChecked = false;
+    static bool isMetro = false;
+    if (alreadyChecked) {
+      return isMetro;
+    }
+
+    HMODULE user32DLL = LoadLibraryW(L"user32.dll");
+    if (!user32DLL) {
+      return false;
+    }
+
+    typedef BOOL (WINAPI* IsImmersiveProcessFunc)(HANDLE process);
+    IsImmersiveProcessFunc IsImmersiveProcessPtr =
+      (IsImmersiveProcessFunc)GetProcAddress(user32DLL,
+                                              "IsImmersiveProcess");
+    FreeLibrary(user32DLL);
+    if (!IsImmersiveProcessPtr) {
+      // isMetro is already set to false.
+      alreadyChecked = true;
+      return false;
+    }
+
+    isMetro = IsImmersiveProcessPtr(GetCurrentProcess());
+    alreadyChecked = true;
+    return isMetro;
+  }
+
+  HMODULE
+  LoadLibrarySystem32(LPCWSTR module)
+  {
+    WCHAR systemPath[MAX_PATH + 1] = { L'\0' };
+
+    // If GetSystemPath fails we accept that we'll load the DLLs from the
+    // normal search path.
+    GetSystemDirectoryW(systemPath, MAX_PATH + 1);
+    size_t systemDirLen = wcslen(systemPath);
+
+    // Make the system directory path terminate with a slash
+    if (systemDirLen && systemPath[systemDirLen - 1] != L'\\') {
+      systemPath[systemDirLen] = L'\\';
+      ++systemDirLen;
+      // No need to re-nullptr terminate
+    }
+
+    size_t fileLen = wcslen(module);
+    wcsncpy(systemPath + systemDirLen, module,
+            MAX_PATH - systemDirLen);
+    if (systemDirLen + fileLen <= MAX_PATH) {
+      systemPath[systemDirLen + fileLen] = L'\0';
+    } else {
+      systemPath[MAX_PATH] = L'\0';
+    }
+    return LoadLibraryW(systemPath);
+  }
+}
+
+#endif